Reduced use of synthetic fertilizer will be critical for reducing dead zones

Aug 13, 2014

Photo Credit: Calsidyrose

A new study published in the journal Nature Geoscience found that the Mississippi River is inundated by the amount of nitrogen runoff from farms, resulting in large-scale marine life die-offs, or dead zones, in the Gulf of Mexico. Last year this dead zone clocked in at 5,840 square miles, larger than the state of Connecticut. In healthy aquatic conditions river sediments will filter out nitrates, preventing downstream dead zones. Unfortunately, the large scale use of synthetic fertilizer has overwhelmed this natural cleansing process. The study found that while over 99% of the river’s water passes through sediment, there is too much nitrogen in the system for it to be removed before reaching the Gulf. Researchers concluded that reducing inputs will be critical in reduce the size of the Gulf of Mexico’s dead zone. “If you want to curtail this process it has to be at the source, just less inputs from the start,” said Dr. Cardenas, one of the lead authors of the study.